Landlord disappeared - what to do?

[Yulia J.]

My relative is renting an apartment, and the landlord disappeared...not answering phone calls, emails for 3 months or so. They pay rent through cozy. The roof leaks when it rains so they have to move their couch when it rains, no hot water in the bathroom sink, etc etc.  It'd a 4-unit, and other 3 apartments have been vacant since the end of the summer. There is no other mailing address listed on a tax assessor website. They didn't pay their rent this month as they got tired of issues and no way of contacting the landlord. This is a trendy hot area and it's difficult to find an apartment for rent right there where they are. Their 1-year lease expired some time ago. What do they do?